Use SVG variant for Git logo

Summary:
Source: https://git-scm.com/images/logos/downloads/Git-Icon-1788C.eps
Transformed into plain SVG with Inkscape 0.92

Fill color #f03c2e as output by Inkscape seemed off,
replaced with #f05033 as picked from PNG version from the source

Reviewers: KDevelop, apol

Reviewed By: KDevelop, apol

Subscribers: kdevelop-devel

Differential Revision: https://phabricator.kde.org/D4586